It should make us happy, but environmentalists
are deeply alarmed: Prozac, the anti-depression drug, is being taken in such
large quantities that it can now be found in Britain's drinking water.

Environmentalists are calling for an urgent
investigation into the revelations, describing the build-up of the antidepressant
as 'hidden mass medication'. The Environment Agency has revealed that Prozac
is building up both in river systems and groundwater used for drinking supplies.

The government's chief environment watchdog recently held
a series of meetings with the pharmaceutical industry to discuss any repercussions
for human health or the ecosystem.

The discovery raises fresh fears that GPs are overprescribing
Prozac, Britain's antidepressant of choice. In the decade up to 2001, overall
prescriptions of antidepressants rose from nine million to 24 million a year.

A recent report by the Environment Agency concluded Prozac
could be potentially toxic in the water table and said the drug was a 'potential
concern'.

However, the precise quantity of Prozac in the nation's
water supplies remains unknown. The government's Drinking Water Inspectorate
(DWI) said Prozac was likely to be found in a considerably 'watered down'
form that was unlikely to pose a health risk.

Dr Andy Croxford, the Environment's Agency's policy manager
for pesticides, told The Observer: 'We need to determine the effects of this
low-level, almost continuous discharge.'

Norman Baker, the Liberal Democrat's environment spokesman,
said the revelations exposed a failing by the government on an important public
health issue. He added that the public should be told if they were inadvertently
taking drugs like Prozac.

'This looks like a case of hidden mass medication upon the
unsuspecting public,' Baker said. 'It is alarming that there is no monitoring
of levels of Prozac and other pharmacy residues in our drinking water.'

Experts say that Prozac finds its way into rivers and water
systems from treated sewage water. Some believe the drugs could affect their
reproductive ability.

European studies have also expressed disquiet over the impact
of pharmaceuticals building up in the environment, warning that an effect
on wildlife and human health 'cannot be excluded'.

'It is extremely unlikely that there is a risk, as such
drugs are excreted in very low concentrations,' a DWI spokesman said. 'Advanced
treatment processes installed for pesticide removal are effective in removing
drug residues,' he added.